Why Is Acetone Used in Chlorophyll Extraction?
Acetone breaks down chlorophyll's lipid bonds to a plant's thylakoid structure and suspends the pigment in solution. Acetone is the standard solvent for chlorophyll extraction, but ethanol, methanol, propanol, petroleum and N-dimethylformamide can also fulfill this role.
Chlorophyll extraction involves collecting and macerating plant samples, submerging the sludge in acetone or other solvents, centrifuging the resulting mixture, separating the pigments and storing the materials for analysis. An 80 to 100 percent acetone solution is a typical medium, as it is less toxic than other chemicals and yields stable results over 10 to 48 hours. Chlorophyll a, chlorophyll b, carotene and xanthophyll are pigments extracted in the solvent. Processes such as paper or liquid chromatography isolate the chlorophyll a, the target of most research.
Methods and tools vary by the type of assay performed and the plant material sampled. Researchers measure the volume of chlorophyll a to determine the biomass of phytoplankton in an area of the ocean or algae in a fresh-water lake. Ecologists track the health of agricultural plants or forests in the presence of pollution. Instructors provide students with laboratory experience and demonstrate the principals of photosynthesis. Each experiment requires solvent mixtures adapted to the tested plant's structure and chemical makeup.
One of the challenges researchers face is the breakdown of chlorophyll a into chlorophyllide, a pigment that duplicates chlorophyll's light signature and increases its apparent levels. Methods such as boiling the acetone mixture for five to 10 seconds and super-cooling the mixture prevent skewed results.